经常会遇到仪器运行时好时坏的现象，这种现象绝大多数是由于接触不良或者是虚焊造成的。When in use, youoften encounter the phenomenon of good and bad when the instrument is running. This phenomenon is mostly caused by poor contact orvirtual welding.In this case, knocking and hand pressing can be used.

所谓的“敲击”就是对可能产生故障的部位，通过小橡皮鎯头或者其他恶敲击物轻轻敲打插件板或者部件，看看是不是会引起出错或者停机故障。Theso-called "knock"is togently tap the plug-in board orcomponentwith a small rubber hoe orotherevilknocker tosee ifitmay cause an error orshutdown failure.的时侯，关上电源后对插的部件和插头和座重新用手压牢，然后开机试试是不是会消除故障。The so-called "hand pressure"means that when the fault occurs, the components and plugs and sockets that are plugged in are pressed again by hand after the power is turned off,and then thepoweristurned on to tryto eliminate the fault.后又不正常的时侯，最好先将所有接头重插牢再试，如果还是不可以的话，只好另想办法了。If it is found that the shell is normalafterbeing tapped, and then it is abnormalaftertapping, it is best to re-plug all the connectors firmly and try again.If it is still not possible, you have to find another way.

、观察法Observation

利用视觉、嗅觉、触觉。Use vision, smell, and touchwhenusing.某些时候，损坏了的元件会变色、起泡或者出现烧焦的斑点；而烧坏的器件会产生一些特殊的气味；短路的芯片会发烫；用肉眼也能观察到虚焊或者脱焊处。Atsome point, damaged components can become discolored, blistering, orscorched spots;burned devices can produce some special odors; short-circuited chips can become hot; and false soldering orPersondesoldering.

、排除法Exclusion method

The so-called elimination method is to determine the cause of the fault by removing some plug-in boards and components in the plug-in machine.者器件后仪表恢复正常，就说明故障发生在那里。When theinstrument returns to normal afterremoving a certain plug-in board ordevice, it indicates that the fault occurred there.

、替换法Fourth, thereplacement method

者有足够的备件。Requires two instruments of the same model orsufficient spare parts.是不是消除。Replace a good spare with the same component on the faulty machine to see if the faultiseliminated.

、对比法V.Contrast

Two instruments of the same model are required, and one is operating normally.比如，万用表、示波器等。To use this method, you must have the necessary equipment,such as amultimeter and an oscilloscope.：电压比较、波形比较、静态阻抗比较、输出结果比较、电流比较等。According to the nature ofcomparison:voltage comparison, waveform comparison, static impedance comparison, output result comparison, current comparison, etc.

然后检测一些点的信号再比较所测的两组信号，如果有不同，则可以断定故障出在这里。The specific method is: let the faulty meter and normal meter run under the same situation,thencheck the signals at some points and compare the two sets of signals measured.Ifthere are differences, you can conclude that the fault is here.这种方法要求维修人员必须具有相当的知识和技能。Butthis method requires the maintenance personneltohave considerable knowledge and skills.